1. Field of the Invention
The present invention relates to a control device for a motor-driven vehicle such as a hybrid vehicle, an electric vehicle, and a fuel cell vehicle.
Priority is claimed on Japanese Patent Application No. 2005-338467, filed Nov. 24, 2005, the content of which is incorporated herein by reference.
2. Description of Related Art
In a control device for a motor-driven vehicle such as a hybrid vehicle, a storage unit such as a battery is mounted as a drive unit of a motor for producing an assistance driving force to assist an engine or as a unit of recovering regenerative energy that is produced by regeneration by the motor. Since it is necessary to consider the remaining capacity of the storage unit when using it to drive the motor or using the motor as an electrical generator, a zone determining unit is provided that determines whether the remaining capacity of the storage unit is within a normal use zone, an over-discharge zone, or an over-charge zone. The control of the motor is then altered in accordance with the zone that the storage unit is determined to be in by this zone determining unit (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2000-175306).
The aforementioned prior art can be applied in the case of using a storage unit in which changes in the input/output upper limit are comparatively small with respect to the remaining capacity of the battery, as in a nickel-metal hydride (Ni-MH) battery serving as the storage unit. However, when applied to a storage unit in which changes in the input/output upper limit are comparatively large with respect to the remaining capacity, as in a lithium-ion (Li-ion) battery, it is difficult to ensure that the charging and discharging of electrical energy is in balance. That is, even when used near the same remaining capacity, the usage balance of the storage unit differs when producing an assistance driving force and when recovering regenerative energy. As a result, control of the energy balance becomes difficult.
Also, particularly with a Li-ion battery, performance issues arise when the storage unit is left as it is over an extended period of time at a high temperature and with the remaining capacity on the overcharge side. Thus, management also becomes necessary in view of the case of simply leaving the battery as it is.
The present invention therefore has as its object to provide a control device for a motor-driven vehicle that can readily perform energy management even for a storage unit in which the changes in the input/output upper limit are comparatively large with respect to the remaining capacity, as is the case with a Li-ion battery.